EP 0 303 651 B1 discloses a method for interrupting the drive action of an electro-pneumatic chiseling hammer or hammer drill. This method serves to interrupt the drive train in case of jamming in order to protect the user. The jamming of a chiseling hammer is detected on the basis of the position of a tool or of a striking element in a striking mechanism. The jamming of a rotational motion is detected on the basis of acceleration values being exceeded.
Owing to its design, the electro-pneumatic chiseling hammer from DE 28 20 128 cited in EP 0 303 651 B1 switches off when a user lifts the chiseling hammer. A tool engages with a stop installed in the striking axis. A freely moving piston can now move forward to such an extent that the freely moving piston no longer closes off a ventilation opening arranged in the guide tube between the freely moving piston and an exciter piston. The exciter piston can no longer draw in the freely moving piston since a pressure equalization occurs via the ventilation opening. The striking mechanism is thus deactivated in a passive manner. As soon as the user puts down the chiseling hammer, the freely moving piston is pushed through the tool via the ventilation opening. The exciter piston can once again draw in the freely moving piston and the striking mechanism is active.